Deficit symptoms in chronic schizophrenia are particularly resistant to treatment. Indeed, the most common drugs used to treat schizophrenia, the neuroleptics, many indirectly intensify deficit symptoms by virtue of their non-specific blockade of all the subtypes of dopamine receptors. This study tests the hypothesis that the coadministration to schizophrenics "protected" by neuroleptic might reduce deficit symptoms without exacerbating psychotic symptoms.